Ask the experts - eye

Q. I’ve worn glasses my entire life and am eager to have LASIK surgery. What is involved in this procedure, and how successful is it?

A. LASIK is a laser procedure that has become the most common surgical correction for farsightedness, astigmatism, and especially for nearsightedness. First, the eye is anesthetized with drops. Then a circular flap of tissue about the size of a contact lens is cut in the cornea. Still partly attached, the flap is held out of the way so the curve of the cornea can be reshaped. The surgeon then directs a
computer-controlled excimer laser at the cornea, vaporizing microscopic layers of tissue with pulses of light without causing heat damage. When that process is complete, the corneal flap is replaced and a shield is placed over the eye; the flap reattaches by itself, without stitches. Following LASIK surgery, most people can return to work after one to three days. A scratchy feeling in the eye may last a day or so.

This kind of refractive surgery provides about 70% of nearsighted people 20/20 vision without corrective lenses. More than 90% of those who have the surgery achieve 20/40 vision—the level required to pass a driver’s license eye exam.

If you decide to have LASIK surgery, choose an ophthalmologist with plenty of experience in performing the procedure and a high rate of success—20/20 vision without corrective lenses. Steer clear of a doctor who says yes to performing LASIK without a careful evaluation. The procedure isn’t right for everyone.

Q. I’ve just heard of a corneal ulcer—and that it requires immediate treatment. What are corneal ulcers, and what harm can they do?

A. A corneal ulcer is an open sore on the cornea, the transparent window that covers the pupil and iris. Symptoms may include pain, a feeling that something’s caught in your eye, aching, sensitivity to bright light, and increased tears. A white spot of pus may appear on the cornea.

An ulcer can develop when eyelids don’t close properly, leading to irritation, damage, and infection. Ulcers can also occur if a foreign object remains trapped in the eye—for example, if contact lenses are worn overnight or not properly disinfected. Ingrowing eyelashes or an in-turned eyelid can cause corneal damage as well. In addition, a recurrence of a viral ulcer on the cornea can be triggered by physical stress or exposure to sunlight.

Corneal ulcers should be treated immediately. Depending on the cause, an eye doctor will prescribe an antibiotic, antiviral, or antifungal drug. Ulcers usually heal with proper care, but they can leave a scar that may impair vision. Possible complications include deep infection, a hole in the cornea, iris dislocation, and permanent damage to the eye. Rarely, a corneal transplant may be needed.

Q. At 45, I’m starting to have to do that arm’s-length maneuver to be able to read a menu or newspaper. I’ve heard that one solution is to divide near and far vision between your two eyes. How does that work?

A. Welcome to middle age. What you’re experiencing is called presbyopia. As we get older, the lenses of our eyes become less flexible. They’re slower to adjust focus when our attention shifts from something at a distance to something up close, and vice versa. The question is how to deal with this annoying situation.

If you don’t have other vision problems, reading glasses may do the trick. If you’re nearsighted or farsighted, you may want to go with glasses with bifocal, trifocal, or progressive lenses. Or you may want to wear contacts, which also come in versions of these all-in-one lenses. But both options have drawbacks, and some people don’t like them.

That’s where “monovision” comes in. By wearing contact lenses with different prescriptions, or byhaving refractive surgery, your dominant (or “sighting”) eye is assigned to far vision and the other eye to near or intermediate vision. You rely mainly on one eye or the other, depending on where your focus is. Not surprisingly, your brain needs time—usually a couple of weeks—to get used to this splitting up of duties. And some people never do adjust. Anyone considering monovision should do a trial run with contacts first—especially if surgery is the chosen method of correction. Ask your eye doctor about the surgical options—LASIK or conductive keratoplasty.

Keep in mind that monovision is a compromise: It provides acceptable overall vision, but neither near nor far vision is perfectly clear. In addition, there is some loss of depth perception, which can affect night driving or playing sports.

People who have “lazy eye” or who need excellent near or far vision for their work shouldn’t consider monovision.